They are installed on separate servers.
RStudio server is localed on VM (Ubuntu 18.04) and rsconnect server is localed on another VM (Ubuntu 16.04).
Logs from RStudio Server:
$ curl -i -L http://OUR_SERVER:3939
HTTP/1.1 307 Temporary Redirect
Content-Type: text/html; charset=utf-8
Location: /connect/
Server: RStudio Connect v1.7.8-7
Set-Cookie: rscid=MTU3NjA3NjM1MXxEdi1CQkFFQ180SUFBUkFCRUFBQU52LUNBQU1HYzNSeWFXNW5EQVlBQkVkVlNVUVNZMjl1Ym1WamRDOXpkRzl5WlM1SFZVbEVfNE1HQVFFRVIxVkpSQUhfaEFBQUFCRF9oUVlCQVFSVlZVbEVBZi1HQUFBQVZmLUVFZ0FROGRlUG9UeGlUQktOQXMtSDJ0SEM0QVp6ZEhKcGJtY01DUUFIWTNKbFlYUmxaQVZwYm5RMk5BUUdBUHk3NGdoLUJuTjBjbWx1Wnd3SkFBZHlaV1p5WlhOb0JXbHVkRFkwQkFZQV9MdmlDSDQ9fJz7byAhqzf6wziZeI0JEZqDHXETShSbKIjeSjqssUw9; Path=/; Expires=Thu, 12 Dec 2019 14:59:11 GMT; Max-Age=86400; HttpOnly
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
Date: Wed, 11 Dec 2019 14:59:11 GMT
Content-Length: 45
HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: must-revalidate, no-cache, max-age=0
Content-Length: 2413
Content-Type: text/html; charset=utf-8
Last-Modified: Wed, 11 Dec 2019 14:15:07 GMT
Server: RStudio Connect v1.7.8-7
Set-Cookie: rscid=MTU3NjA3NjM1MXxEdi1CQkFFQ180SUFBUkFCRUFBQU52LUNBQU1HYzNSeWFXNW5EQVlBQkVkVlNVUVNZMjl1Ym1WamRDOXpkRzl5WlM1SFZVbEVfNE1HQVFFRVIxVkpSQUhfaEFBQUFCRF9oUVlCQVFSVlZVbEVBZi1HQUFBQVZmLUVFZ0FRcXhQeUZzR09Rc2VhZ0ROU0doU0dWUVp6ZEhKcGJtY01DUUFIWTNKbFlYUmxaQVZwYm5RMk5BUUdBUHk3NGdoLUJuTjBjbWx1Wnd3SkFBZHlaV1p5WlhOb0JXbHVkRFkwQkFZQV9MdmlDSDQ9fG8yToQpBmOjFTGQLQPEpoTgJHq0_jh7WyUZu0M3QTMS; Path=/; Expires=Thu, 12 Dec 2019 14:59:11 GMT; Max-Age=86400; HttpOnly
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
Date: Wed, 11 Dec 2019 14:59:11 GMT
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>RStudio Connect</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=5.0" />
<meta name="apple-mobile-web-app-capable" content="yes" />
<!--[if lt IE 9]>
<script src="assets/javascripts/ie.min.js"></script>
<![endif]-->
<!-- jQuery -->
<link rel="icon" type="image/x-icon" href="/favicon.ico" />
<script async src="out/dashboard.bundle.js"></script>
<style>#initialSpinner .dot{width:40%;height:40%;border-radius:50%;position:absolute;-webkit-animation:initialProgressPulse 2s infinite ease-in-out;animation:initialProgressPulse 2s infinite ease-in-out}#initialSpinner .dot.one{top:0;left:30%;background-color:#75aadb}#initialSpinner .dot.two{top:30%;left:0;-webkit-animation-delay:-1.5s;animation-delay:-1.5s;background-color:#75aadb}#initialSpinner .dot.three{bottom:0;left:30%;-webkit-animation-delay:-1s;animation-delay:-1s;background-color:#75aadb}#initialSpinner .dot.four{top:30%;right:0;-webkit-animation-delay:-.5s;animation-delay:-.5s;background-color:#75aadb}#initialSpinner{display:block;width:100%;height:100%;position:relative;-webkit-animation:rotate 2s infinite linear;animation:rotate 2s infinite linear}@-webkit-keyframes rotate{100%{-webkit-transform:rotate(360deg);transform:rotate(360deg)}}@keyframes rotate{100%{-webkit-transform:rotate(360deg);transform:rotate(360deg)}}@-webkit-keyframes initialProgressPulse{0%,100%{-webkit-transform:scale(.1);transform:scale(.1);opacity:.1}50%{-webkit-transform:scale(1);transform:scale(1);opacity:1}}@keyframes initialProgressPulse{0%,100%{-webkit-transform:scale(.1);transform:scale(.1);opacity:.1}50%{-webkit-transform:scale(1);transform:scale(1);opacity:1}}#initialSpinnerWrapper{margin-left:auto;margin-right:auto;height:150px;width:150px;margin-top:150px}</style>
</head>
<body>
<app-layout>
<standard-page>
<ui-view></ui-view>
</standard-page>
</app-layout>
<div id="initialSpinnerWrapper" ng-if="false">
<div id="initialSpinner">
<div class="dot one"></div>
<div class="dot two"></div>
<div class="dot three"></div>
<div class="dot four"></div>
</div>
</div>
<div class="taskui-global" taskui="taskui"></div>
</body>
</html>